POS1173 LONG-TERM ANALYSIS OF RELAPSE RATES IN A EUROPEAN ANCA-ASSOCIATED VASCULITIS (AAV) COHORT FOR GPA AND MPA
Authors: S. Krämer, T. Rauen, K. Pruin, T. Anslinger, M. Busch, T. Schmitt, R. Bergner, S. Mosberger, T. Neumann
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Therapeutic interventions for ANCA-associated vasculitides (AAV) dramatically changed over the last two decades. Especially the introduction of rituximab into the therapeutic portfolio significantly improved outcome data, whereby relapse rates in previous cohorts were mostly reported from only up to two-year periods. <h3>Objectives</h3> With the present study, we thought to retrospectively investigate the overall relapse rates in a large European AAV cohort. <h3>Methods</h3> Data of patients with newly diagnosed GPA and MPA (retrospectively classified on ACR/EULAR 2022 criteria) from four tertiary referral centers in Germany and Switzerland were collected between 2000 and 2021. Events were captured during routine out-patient visits and hospital admissions. A relapse was considered at the time of any increased vasculitis activity, i.e. therapeutic necessity to increase glucocorticoids ≥10 mg prednisolone per day. First relapse occurrence was analyzed as time-to-event analysis and number of cases for each group. Differences were compared by ANOVA- and X<sup>2</sup>-test, respectively. <h3>Results</h3> Our data set comprised a total of 338 patients, 46.2% women (mean age of 59.2±14.7 years). Of these, 203 cases (60.1%) were classified as GPA and 135 (39.9%) as MPA. At initial presentation, 74.9% of patients exhibited renal, 50.9% pulmonary and 35.2% ENT involvement. Over a median follow-up period of 58.7 months (IQR 29.4 to 101.7) we observed an overall relapse rate of 35.8% in the entire cohort and median time to first relapse was 32.6 months (IQR 11.9 to 56.9). Following three years after initial diagnosis, we observed a significant difference, yielding 46 relapses (22.7%) in GPA and 19 (14.1%) in MPA patients at that time (p&lt;0.05). Over the entire follow-up, 86 patients with GPA experienced at least one relapse (42.4%) whereas in MPA only 35 (25.9%) patients relapsed (p&lt;0.01). In addition, log-rank test revealed a significant difference in relapse over time (p&lt;0.05, Figure 1). The median time to the first relapse did not differ significantly between GPA and MPA patients (GPA: 27.9 months, IQR 13.6 to 55.9, vs. MPA: 35.1 months, IQR 8.6 to 55.9, p=0.458). <h3>Conclusion</h3> In our European AAV cohort, we observed an overall relapse rate of 35.8% for both AAV entities with the first relapse occurring after a median of 32.6 months. GPA patients exhibited consistently higher relapse rates than those with MPA over the entire observational period. We propose that future analyzes of relapse rates should cover a minimum of three years to capture roughly half of all expected events. <h3>REFERENCES:</h3> NIL. <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> Stefan Krämer: None declared, Thomas Rauen Consultant of: Vifor, Kristian Pruin: None declared, Teresa Anslinger: None declared, Martin Busch: None declared, Tobias Schmitt: None declared, Raoul Bergner Speakers bureau: Abbvie, Bristol Myers Squibb, Chugai, Glaxo Smith Kline, Galapagos, MSD, Novartis, Consultant of: Galapagos, Vifor, Sebastian Mosberger: None declared, Thomas Neumann Speakers bureau: Roche Pharma (Suisse) AG, GlaxoSmithKline AG, Celgene Switzerland, UCB-Pharma AG, Janssen-Cilag AG, Vifor Pharma Switzerland, Novartis Switzerland, Consultant of: Roche Pharma (Suisse) AG, GlaxoSmithKline AG, Celgene Switzerland, AstraZeneca GmbH, Janssen-Cilag AG, Amgen Switzerland AG, Vifor Pharma Switzerland, Grant/research support from: Vifor Pharma Switzerland.